[Effect of methotrexate on the activity of DNA-dependent RNA polymerases (A and B) in the spleen of mice infected with Rauscher leukemia virus and on the development of virus-induced leukemia].

Methotrexate was shown to inhibit development of Rausher's leukosis and growth of spleen. Activity of DNA-dependent RNA polymerases A and B was distinctly altered. The activity of RNA polymerase B was increased two-fold within the first days of the leukosis development; RNA polymerase A was activated five-fold in the course of subsequent progression of the impairment. Methotrexate inhibited the RNA polymerase activity in leukemic spleens. As suggested by correlation between weight of the spleen and the activity of RNA polymerases A and B, the enzymatic activity may be considered as a marker of the leukosis development.